RAMDISK is a memory management technique in which a portion of volatile system memory is used as a mass storage device under program control, referred to herein as a “volatile disk drive (VDD) memory.” Operating system (OS) file operations to a RAMDISK are significantly faster than OS operations to traditional hard disks. As a result, a RAMDISK can drastically increase system performance by placing most frequently used programs and files within the portion of system memory allocated to the RAMDISK. Although the RAMDISK does not retain stored information once the system is switched off, the RAMDISK memory management technique is very useful for temporary storage and caching of data, which is stored in a normal OS file format. Typically, RAMDISKS are used in web/file servers to cache frequently used files from a pool of mass media storage.
Conventionally, the driver used to implement RAMDISK is fully implemented in software. As a result, when a program or process wants to read/write a file in a RAMDISK, the RAMDISK driver is invoked. This driver first identifies how the requested file is mapped to system memory locations, which are reserved for the RAMDISK. Once identified, the driver transfers data to/from the RAMDISK's memory to/from the requesting processes' memory. Generally, this is performed with the aid of the CPU where the driver directs the CPU to request data from the RAMDISK portion of system memory.
Unfortunately, the CPU (central processing unit) is required to manage both data transfers and file management functions for the RAMDISK driver. Although the RAMDISK memory management technique is much faster than the use of conventional storage drives, a RAMDISK driver utilizes numerous CPU cycles to transfer data between RAMDISK locations and application locations. Furthermore, implementing a RAMDISK for a memory exceeding 4 gigabytes (GB) (32-bit address), required the RAMDISK driver to use the CPU's page address extension (PAE) mode. Unfortunately, PAE mode, itself, introduces additional performance penalties, not only on the RAMDISK driver, but to all processes running within the system.